There has thus far been available an airbag device for a driver seat of the automobile equipped with an airbag cover, formed by fixedly attaching a decorative member, such as a horn unit and so forth, to a part on the extension line of a steering shaft of a steering system, and installing an airbag folded around the decorative member so as to be contained in the airbag cover. However, in assembling this airbag device by attaching the airbag to the airbag cover, it has been found difficult to implement such attachment by aligning an attachment bolt insertion hole of the airbag with an attachment bolt of the horn unit, so that an attachment work has been time-consuming and in addition, there has been a possibility that damage occurs to the periphery of an inflator attachment opening of the airbag when securing the periphery of the inflator attachment opening of the airbag with a fixture support member after attachment.
FIG. 16 is a schematic view showing an airbag device MR as an example, and FIG. 17 is a perspective view of an airbag to be attached to the airbag device MR. The airbag device MR is to be incorporated into a steering system of a vehicle, comprising a horn unit 40R, an airbag 10R, an inflator 30R and an airbag cover 16R, as shown in FIG. 16. For convenience's sake in describing a conventional technology hereinafter, a side of the horn unit 40R, on the side of a driver seat, is referred to as a front side while an opposite side thereof is referred to as a back side.
A hole is made at the center of a depressed part 16aR of the airbag cover 16R, and an attachment bolt 40aR provided at the center on the back side of the horn unit 40R is inserted into the hole, thereby securing the horn unit 40R to a connecting member 20R. The connecting member 20R is clamped (not shown in the figure) between a cushion ring 22R clamping the airbag 10R and a base plate 24R to which the inflator 30R is secured.
As shown in FIG. 17, the airbag 10R comprises an airbag main body 10aR and a tubular tether belt 11aR for restricting an inflation-expansion length of the airbag main body 10aR, and the airbag main body 10aR is formed in the shape of a bag that is inflatable and expandable into a flat spherical shape (an ellipsoidal shape) by stitching respective outer circumferential edges of two pieces of cloth substantially circular in shape with each other. An inflator attachment opening 10ahR is formed substantially at the central part of the airbag main body 10aR on the back side thereof, and small screw holes 10bR for inserting screws of the cushion ring 22R respectively are made around the inflator attachment opening 10ahR. The tubular tether belt 11aR is formed in an insertion hole 10hR provided substantially at the central part on the surface of the airbag main body 10aR of the airbag 10R, and an end of the tubular tether belt 11aR is provided with an attachment bolt insertion hole 11ahR for inserting the attachment bolt 40aR of the decorative member therethrough.
The tubular tether belt 11aR of the airbag 10R is secured between the depressed part 16aR of the airbag cover 16R and the connecting member 20R while the inflator attachment opening 10ahR of the airbag 10R is secured between the cushion ring 22R fitted with the connecting member 20R and the base plate 24R.
A method for attaching the airbag 10R to the airbag cover 16R comprises the steps of aligning a position of the hole of the airbag cover 16R with that of the attachment bolt insertion hole 11ahR of the tubular tether belt 11aR of the airbag 10R when inserting the airbag 10R into the airbag cover 16R, and subsequently aligning a hole of the connecting member 20R with the attachment bolt insertion hole 11ahR, thereby overlaying the base plate 24R on the connecting member 20R.
Thereafter, the bolt 40aR of the horn unit 40R is inserted into the hole of the airbag cover 16R, thereby secured to the connecting member 20R. However, if the position of the attachment bolt insertion hole 11ahR of the tubular tether belt 11aR of the airbag 10R deviates from the hole of the airbag cover 16R, positioning from the backside is executed by making use of an inflator attachment opening of the base plate 24R in order to implement positional alignment. In such a case, the attachment bolt insertion hole 11ahR of the tubular tether belt 11aR of the airbag 10R, on the front side of the connecting member 20R, is hidden behind the front side of the connecting member 20R, so that positioning of the attachment bolt insertion hole 11ahR will become difficult to implement, thereby prolonging work time. Furthermore, when securing the periphery of the inflator attachment opening 10ahR of the airbag 10R clamped between the cushion ring 22R fitted with the connecting member 20R and the base plate 24R, there arises a possibility of the periphery of the inflator attachment opening 10ahR of the airbag 10R being damaged by an edge of the cushion ring 22R.
Patent Document 1: JP 2004-22943 A